The present disclosure relates to a droplet generator for a continuous stream ink jet printhead, particularly for a binary array printhead.
Continuous ink jet (CIJ) is a form of ink jet that operates on the theory of selectively charging and deflecting drops in flight. Drops are continuously generated at the nozzle by inducing break-off from a pressurized continuous stream of ink in the presence of a variable electrostatic field created by a charging electrode that places a discrete charge on selected drops. Drops subsequently pass through an electrostatic field wherein the field potential induces deflection on the charged drops in order to direct them to print or direct them into an ink catcher to be reused in the ink system. This same mechanism is often used in binary array CIJ printing which is a type of inkjet that includes an array of jets and that can print at relatively high resolutions of at least 128 by 128 dots per inch (dpi).
Binary printheads use actuators to vibrate ink and eject droplets thereof from the printhead. The actuators need to be precisely situated for the printhead to work properly. A difficulty in prior art actuators is that the components are manufactured separately and then assembled. Manufacturing and assembly variations lead to poor jet break-up uniformity. Consequently, a very high accuracy is required of the physical dimensions of the structural components of the generator. Further, very little stray is permitted in operating parameters of the generator such as ink composition and temperature.